Atom - e - Occurs
Characters: e
Arity: dyadic
This atom is dyadic, which means it takes two arguments.
Functionality
Return 1 if x occurs in y and 0 otherwise.
Details
This takes the element on the left and the list on the right. If you need the inverse, instead of e@, consider using i (Index Of). It does not return a boolean value, but you can use it if you only need to check truthiness/falsiness.